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Components and Circuits For discussions about component types, alternatives and availability, circuit configurations and modifications etc. Discussions here should be of a general nature and not about specific sets. |
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26th Jan 2022, 11:35 pm | #1 |
Octode
Join Date: Jun 2013
Location: Huddersfield, West Yorkshire, UK.
Posts: 1,782
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Dymar Modulation meter.
Hi Peeps. I am looking at making a "chinese" copy of the Dymar Modulation meter, however they use two IC's that I have no data on....PA230 some sort of RF opamp. Might even be a LM709 as it has external compensation.
Any ideas ??
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Should get out more. Regards Wendy G8BZY |
27th Jan 2022, 12:17 am | #2 |
Nonode
Join Date: Oct 2010
Location: Tintinara, South Australia, Australia
Posts: 2,324
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Re: Dymar Modulation meter.
How about getting a bit more modern and building something a little simpler?
https://www.vk5dj.com/deviation.html Only extra needed is a scanner (as in radio scanner) to tap in to. |
27th Jan 2022, 8:58 am | #3 |
Heptode
Join Date: Mar 2008
Location: Forest of Dean, Gloucestershire, UK.
Posts: 647
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Re: Dymar Modulation meter.
I can confirm that the “use an old scanner” approach works well. I have such a modulation meter that I build around 30 years ago to a designing published in 73 magazine. I don’t use it anymore but when I checked it’s calibration a couple of years ago it was still impressively good for such a simple design.
The main down side is that you need to get access to some sort of “standard” in order to set or confirm the calibration (in my case I borrowed a service monitor from work). Of course the scanner needs to cover the frequencies of interest and needs the right channel spacing for what you want. Hugh |
27th Jan 2022, 9:58 am | #4 |
Dekatron
Join Date: Jan 2004
Location: Newcastle upon Tyne, Tyne & Wear, UK.
Posts: 8,171
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Re: Dymar Modulation meter.
Hi Wendy, I may have some '709's from way back if you need any
Ed |
27th Jan 2022, 11:37 am | #5 |
Octode
Join Date: Jun 2013
Location: Huddersfield, West Yorkshire, UK.
Posts: 1,782
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Re: Dymar Modulation meter.
Hi Peeps. Haa Haa...... You convinced me Terry. I will do a pcb.. and go from there...
Stupidly I gave away a Dymar Mod meter about a year ago. It was bought as a "donor" and sat in the storage area.... I thought... what a pity to destroy it... so I offered it in the forum. Well now... building my 2 M TX/RX it is only right that the levels are set correctly and I have a ICOM ICR 7100...... so... there you go. Thanks Ed... but I wont need them now..... I do a bit on the VHF radio.. then have a few days off....and look at other things...pity I have a super mirrored moving coil meter.....I May just incorporate it
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Should get out more. Regards Wendy G8BZY |